Dispensing device

ABSTRACT

A device for dispensing individual doses of powder from respective pockets of a disc-shaped carrier by outwardly rupturing a lidding foil by means of pressure on an opposite side surface, the device providing individual respective deaggregation flow paths for each pocket, split airstreams allowing improved entrainment of powder, a cam mechanism for outwardly rupturing the pockets, an indexing mechanism linked to the cam mechanism and a dose counter.

This application is a continuation of application Ser. No. 12/795,206,filed Jun. 7, 2010, which is a continuation of application Ser. No.10/565,064, filed Jul. 7, 2006, now U.S. Pat. No. 8,181,645, issued May22, 2012, which claims the benefit of International Patent ApplicationNo. PCT/GB2004/002748, filed Jun. 25, 2004, which claims the benefit ofGreat Britain Patent Application No. 0315509.0, filed Jul. 2, 2003, allof which are incorporated by reference herein in their entireties.

The present invention relates to a dispensing device, in particular fordispensing individual doses of powder from respective pockets of acarrier.

A wide variety of devices are known for dispensing doses of medicamentin the form of powder for inhalation. Devices are known which contain astore of powdered medicament from which individual doses are metered asrequired. Devices are also known which include carriers having aplurality of pockets containing respective doses of powder. Thesecarriers are typically in the form of blister-packs. All of thesedevices face problems of providing reliable, repeatable and accurateinhaled amounts of powder.

There are problems in ensuring that all of a dispensed dose of powder isentrained into the airstream for inhalation. Furthermore, some of thepowder which is originally provided for inhalation may adhere tosurfaces within the device. This will reduce the inhaled dose. However,more importantly, after a number of uses, previously adhered powder maybecome dislodged, thereby resulting in an unwanted and undesirableincrease in the inhaled dose. There are other problems in providingrepeatable and consistent release of powder into the inhalationairstream as desired.

In attempting to reduce these problems, previous devices suffer problemsof increased size, complexity and/or cost.

U.S. Pat. No. 4,811,731 describes an inhaler having a support for ablister pack having an annular array of blisters. The support faces atray having upstanding walls defining a flow path to a mouthpiece. Inuse, the support and blister pack is consecutively indexed such thatpowder from respective blisters is dispensed via the flow path definedby the tray and upstanding walls. Because the same tray and upstandingwalls are used for all of the blisters, there is the problem that powdercan become adhered to the tray and upstanding walls and then dislodgedsubsequently.

It is an object of the present invention to overcome or at least reducethese problems.

According to the present invention, there is provided a device fordispensing individual doses of powder from respective pockets of acarrier, the device including a support for a carrier having a pluralityof pockets containing respective doses of powder and a mouthpiecethrough which to inhale an airstream carrying a dose of powder, thedevice further including walls for defining individual respective firstflow paths downstream of each respective pocket of a supported carrierwherein each individual respective first flow path is defined entirelyby respective walls unique to that individual respective first flowpath, is for connecting the corresponding respective pocket to themouthpiece and is for deaggregating powder in the airstream.

In this way, each pocket of powder is provided with its own first flowpath such that any powder which does adhere to the walls of that firstflow path will not affect subsequent dispensing inhalations through thedevice. There are no walls in common between respective first flow pathssuch that powder adhering to walls of a first flow path will not affectsubsequent doses. In particular, subsequent inhalations will drawairstreams through the first flow paths of the respective pockets beingdispensed such that, even if previously adhered powder is dislodged inthe first flow paths of previously dispensed pockets, this powder willnot be part of the inhalation airstream and, hence, will not be inhaledby the user.

According to the present invention, there is also provided a device fordispensing individual doses of powder from respective pockets of acarrier, the device including: a support for a carrier having aplurality of pockets containing respective doses of powder; and amouthpiece through which to inhale an airstream carrying a dose ofpowder; the device further including: walls for defining individualrespective first flow paths downstream of each respective pocket of asupported carrier for connecting the corresponding respective pockets tothe mouthpiece and deaggregating powder in the airstream; an arrangementfor moving individually each pocket from a respective storage positionto a respective discharge position, wherein each pocket, in therespective discharge position, forms an integral part of the individualrespective first flow path.

Preferably, the device is for use with a carrier having pockets providedwith a lidding sheet, the device allowing the lidding sheet to beruptured as a consequence of moving a pocket from a respective storageposition to a respective discharge position.

Preferably, the device further includes walls defining a second flowpath connecting with the mouthpiece and bypassing the pockets.

This allows an increase in flow volume through the device and areduction in the resistance to flow, such that a user may more easilyinhale through the device. This is most important where the size of thepockets is not sufficient to allow the flow volume to reach thatnecessary to carry medicament into the lung. Furthermore, it alsobecomes possible to entrain powder in the airstream over a small, butsustained, period of time, rather than substantially all at once. Thepowder may be entrained during a mid-portion of inhalation, therebyimproving the transfer of powder to the user. The device shouldpreferably provide similar performance over flow rates ranging from 28.3l/min to 60 l/min and should preferably have a pressure drop notexceeding 4 kPa at 60 l/min.

Preferably, with the device configured to dispense a dose of powder fromone of the pockets of the supported carrier, the respective flow pathconnects with the second flow path downstream of the bypass and at anangle such that substantially no powder impacts with the walls definingthe second flow path. Some impact could be allowed, but then preferablysubstantially no deposition occurs. Some powder could be allowed to bedeposited on the walls defining the second flow path, but thenpreferably, with repeated use of the device and the second flow path, nomore than 25% or preferably no more than 15% of a dose remains depositedon the walls defining the second flow path. It will be appreciated thatthe airstream through the second flow path also acts to scour orscavenge powder deposited on the walls defining the second flow path.

In other words, it is thus possible for a part of the second flow pathto be used consecutively for all of the pockets of the carrier. However,since the respective first flow paths provide the requireddeaggregation, the second flow path can be arranged to provide a minimumamount of turbulence and to avoid substantially any powder adhering toits walls. By providing an appropriate angle at which the first flowpaths meet the second flow path, powder can substantially be preventedfrom impacting the walls of the second flow path when it joins thesecond flow path from the respective first flow path.

Preferably, where the respective first flow path connects with thesecond flow path, the angle is less than 45 degrees, more preferablyless than 30 degrees.

This ensures that substantially no powder adheres to the walls definingthe second flow path.

Preferably, the support for the carrier and the walls defining the firstflow path are moveable with a supported carrier so as to selectivelyconnect respective first flow paths with the second flow path and,hence, selectively dispense doses of powder from respective pockets ofthe supported carrier.

In this way, the device can be provided with a single mouthpiece anddispensing mechanism so as to minimise cost and complexity and yet stillprovide each pocket of the carrier with its own respective first flowpath in which deaggregation and any adherence of powder occurs.

In a preferred embodiment, the carriers are disc-shaped with acircumferential array of pockets. In this embodiment, the pockets andtheir respective first flow paths are indexed by rotation relative tothe second flow path and mouthpiece so as to dispense consecutivelydoses of powder for inhalation through the mouthpiece.

Preferably, the walls defining the first flow paths include, upstream ofthe pockets, respective portions of relatively reduced cross-sectionalarea orientated so as to be directed towards respective pockets anddirect a relatively high velocity airstream into the respective pockets.

Indeed, according to the present invention, there is also provided adevice for dispensing a dose of powder from a pocket of a carrier, thedevice including a support for a carrier having a pocket containing adose of powder and a mouthpiece through which to inhale an airstreamcarrying a dose of powder, the device further including walls definingfirst and second flow paths connecting with the mouthpiece, the firstflow path connecting the pocket of the supported carrier to themouthpiece and the second flow path bypassing the pocket, wherein thewalls defining the first flow path include, upstream of the pocket, aportion of relatively reduced cross-sectional area orientated so as tobe directed towards the pocket and direct a relatively high velocityairstream into the pocket.

In this way, the high velocity airstream can erode the powder in thepocket so as to progressively entrain it into the airstream, rather thanmerely attempt to flush the powder from the pocket. This results in thepowder being entrained into the airstream over a sustained period oftime. The time is preferably within the range of 0.01 s to 1.0 s andmore preferably in the range of 0.2 s to 0.5 s. This provides improvedinhalation characteristics.

Furthermore, by virtue of the second flow path in conjunction with thefirst flow path, resistance to airflow can be reduced and volume ofairflow increased. The portions of relatively reduced cross-sectionalarea produce a small high velocity stream suitable for eroding thepowder. By providing these in conjunction with the second flow path, theuser is still able to inhale relatively easily through the device,despite the restriction of the respective reduced cross-sectional areaportions.

As will be appreciated, this arrangement has similar advantages whenused with a carrier having only a single pocket and, hence, only asingle first flow path.

Preferably, each portion has a cross-sectional area between 50% and 66%of the cross-sectional area of the smallest part of the second flowpath. Indeed, preferably, the cross-sectional areas of the non-reducedcross-section parts of each flow path are provided between 110% and 150%of the minimum values in their own path order to maintain the high airvelocities required to keep the powder entrained without contributingsignificantly to pressure drop.

This allows a suitably high velocity airstream to be directed into apocket without unduly increasing the overall resistance to inhalationand allowing a sufficiently high overall volume of airflow.

In the preferred embodiment, there is another second flow path for theother side of the device and its corresponding carrier. In use, apatient inhales through both second flow paths whilst drawing powderfrom the first flow path in use. Each of the second flow paths isexpected to carry approximately 40% of the total inhaled air for anaverage use.

Actual requirements will vary depending upon the nature of the powderand the intended user. For an easily dispensed powder, the portionforming the inlet to the pocket can be small and, for a child or patientwith COPD (Chronic Obstructive Pulmonary Disease), the total pressuredrop should be low. In this case, an inlet portion could be providedwith a cross-sectional area of 2 mm² and a bypass second flow path witha minimum cross-sectional area of 8 mm², resulting in a ratio of 25%. Onthe other hand, with sticky powder for a healthy adult, the inletportion could be provided with a cross-sectional area of 4 mm² togetherwith a bypass second flow path having a minimum cross-sectional area of6 mm², resulting in a ratio of 66%. Of course, intermediate values arealso possible and a preferred arrangement has an inlet portion ofapproximately 3 mm² with a second flow path minimum cross-sectional areaof 6 mm², resulting in a ratio of 50%.

Referring to FIG. 21( a) of the accompanying drawings, it will be notedthat it is important for the cross sectional areas A₁, A₂ and A₃ to bebetween 120% and 200% of the smallest cross sectional area B for thebypass flow. Similarly the cross sectional areas C₁, C₂ and C₃ should bebetween 120% and 200% of the smallest cross-sectional area of theportions D for the flow path through a pocket. The combined flow pathcross sectional area E should then be greater than A₃ plus C₃ such thatair velocity in the pocket is not reduced.

For this arrangement, the pressures at A₃, C₃ and E can all be the sameand equal to or less than that in the mouth of the patient. The wholepressure drop due to inhalation then occurs across both B and D. Forcohesive formulations, it is advantageous to have the maximum airvelocity through the pocket portion. This may be achieved by minimizingthe pressure at C₃ during inhalation. If the mouthpiece is shaped tocause the air to expand with laminar flow by the use of a smalldivergence angle, typically less than 10 degrees, then it is possible tocause the pressure at C₃ to be below the pressure in the mouth, thusincreasing the air velocity through the pocket portion.

The ratio of B to D sets the ratio of air flowing through the bypass andthe pocket.

The sum of the areas B and D sets the overall flow resistance and ispreferably set to give 3 kPa to 4 kPa at 60 l/m.

For the preferred embodiment, storing individual doses of powder ofapproximately 20 mg in pockets having volumes of approximately 30 mm³,each portion preferably has a cross-sectional area of between 2.0 mm²and 10.0 mm², more preferably between 2.0 mm² and 5.0 mm².

The reduced cross-section is selected to be between 50% and 90% of thearea which, for the normal range of inhalation rates and volumes,provides a suitable high velocity airstream into the pocket.

FIG. 21( b) of the accompanying drawings illustrates the preferred crosssections for a particular embodiment. In particular, the minimum crosssectional area B for the bypass flow is approximately 5.0 mm², theminimum cross sectional area D for the pocket flow is approximately 3.8mm² and the combined flow path cross sectional area E is approximately12.0 mm².

According to the present invention, there is also provided a device fordispensing individual doses of powder from respective pockets of a pairof carriers, the device including a support for two disc-shapedcarriers, each disc-shaped carrier having at least one substantiallyplanar first side surface having an annular array of cavities in whichrespective pockets are formed and a respective first lidding sheetsealed to the first side surface for enclosing the cavities wherein thesupport is for rotatably supporting the carriers about a substantiallycommon axis, a mouthpiece through which to inhale an airstream carryingpowder from the carriers, a dispensing mechanism for releasing into theairstream the powder of a respective pocket of a supported carrier andan indexing mechanism for rotating the carrier relative to thedispensing mechanism so as to enable powder to be released fromdifferent pockets.

This arrangement provides an extremely compact and efficient way ofholding and dispensing a plurality of pockets of powder. A singledispensing mechanism can be provided for both carriers and the carriersmay easily be moved so as to selectively bring each of their pockets intine with the dispensing mechanism and an airstream for carrying powderto the mouthpiece.

The arrangement can be used in conjunction with the features describedabove and is particularly effective in this regard.

Preferably, between consecutive dispensing of powder from one of saidcarriers, the indexing mechanism is operable to rotate both of saidcarriers relative to the dispensing mechanism.

In other words, where powder is dispensed from a first disc, powder willalso be dispensed from the second disc before more powder is dispensedfrom the first disc. Hence, similarly, preferably, between consecutivedispensing of powder from the other of said carriers, the indexingmechanism is operable to rotate both of said carriers relative to thedispensing mechanism.

Preferably, the dispensing mechanism is operable to release powder froma pocket of each carrier for a single inhalation of both respectivepowders simultaneously.

In other words, powder is dispensed from the pocket of a first disc andalso powder is dispensed from a pocket of a second disc. The user maythen inhale the powder dispensed from both discs simultaneously. Thisallows two different medicaments to be administered simultaneouslywithout the medicaments coming into contact until immediately before orindeed during the inhalation process.

Preferably, the mechanism is operable to dispense medicament from apocket of each disc simultaneously.

Hence, having rotated the discs to an appropriate position with anunopened pocket of each disc available, the mechanism then opens bothpockets together in one operation.

Alternatively, the dispensing mechanism may be operable to releasepowder from a pocket of one of the carriers for inhalation then torelease powder from a pocket of the other of the carriers forinhalation.

In this way, a user may administer two different pharmaceuticalsimmediately one after the other or may use the inhalation device as partof a course of treatment whereby different medicaments are administeredalternately after, predetermined periods of time. By way of example, asteroid compound could be dispensed from one disk and a long actingbeta-agonist from the other disk for the treatment of e.g. asthma orchronic obstructive pulmonary disease: Examples of long actingbeta-agonists include formoterol and salmeterol and examples of steroidsinclude fluticasone propionate, budesonide and monetasone furoate.

Indeed, the inhalation device could include three or more discs suchthat more complicated courses of pharmaceuticals could be administered.Indeed, the mechanism could be arranged so as to dispense apredetermined number of doses from one disc before administering a dosefrom the other disc.

In certain, embodiments, the mechanism may be operable to release powderfrom a pocket of one carrier and from a pocket of the other carrierconsecutively.

Such a system could be used when the powder of the two pockets isinhaled together or consecutively.

A device may be provided with two of said disc shaped carriersrespectively containing powder of different medicaments.

This allows, as mentioned above, different medicaments to be dispensedfrom the same device.

Preferably, between consecutive dispensing of powder, the indexingmechanism is operable to rotate one of said carriers in turn betweenconsecutive dispensing positions before rotating the other of saidcarriers.

In other words, the indexing mechanism is arranged to move one of thecarriers between consecutive pockets whilst the other carrier remainswhere it is.

The dispensing mechanism, and the indexing mechanism may together beoperable to dispense powder from all of the pockets from one of the saidcarriers before dispensing powder from pockets of the other of saidcarriers.

This allows the use of an indexing mechanism which always moves one orother of the carriers onto its next position.

According to the present invention, there is also provided a device fordispensing individual doses of powder from respective pockets ofcarrier, the device including a first support for a first carrier havingfirst and second side surfaces opposite each other, an array of cavitiesin which respective pockets are formed and a first lidding sheet sealedto the first side surface, a first prodger member moveable towards andaway from the second side surface of a supported first carrier between aretracted and an extended position and a cam member adjacent to andmoveable generally parallel with the second side surface of a supportedcarrier between a rest position and a primed position, wherein the cammember has a first cam surface for engaging with the first prodgermember such that movement of the cam member from the rest position tothe primed position moves the prodger member from the retracted positionto the extended position so as to press upon the second side surface ofa supported first carrier and outwardly rupture the first lidding sheetof the supported first carrier.

In this way, a compact and effective mechanism is provided for openingindividual pockets of a carrier. The cam member may be provided with arelatively large amount of movement, but, since this is generallyparallel to the plane of the carrier, this need not take up excessivespace. At the same time, converting this large amount of movement toonly the small amount of movement required for the prodger member, theuser is given a large mechanical advantage such that dispensing of thepowder from a pocket is relatively easy and well controlled.

Preferably, the device further includes a second support for a secondcarrier having first and second side surfaces opposite each other, anarray of cavities in which respective pockets are formed and a firstlidding sheet sealed to the first side surface, the first and secondcarriers being supported with respective second side surfaces facingeach other, a second prodger member moveable towards and away from thesecond side surface of a supported second carrier between a retractedand an extended position, wherein the cam member has a second camsurface for engaging with the second prodger member such that movementof the cam member from the rest position to the primed position movesthe prodger member from the retracted position to the extended positionso as to press upon the second side surface of a supported secondcarrier and outwardly rupture the first lidding sheet of the supportedsecond carrier.

In this way, the same advantages are achieved for a second carrier.Furthermore, these advantages are achieved using only a single cammember for dispensing from both of the two carriers. Hence, the deviceis very efficient in its use of space.

The device may be arranged as described above so as to achieve the sameadvantages. Thus, preferably, the device further includes an indexingmechanism for moving the first and second supports relative to the firstand second prodger members so as to selectively align pockets of thecarrier with respective prodger members.

In this way, the carriers are efficiently moved and located with respectto the dispensing mechanism and the mouthpiece.

Preferably, the indexing mechanism is arranged such that, with one ofthe first and second prodger members aligned with a respective pocket,the other of the first and second prodger members is aligned betweenrespective pockets, whereby movement of the cam member from the restposition to the primed position causes only one of the first and secondprodger members to outwardly rupture the first lidding sheet of thecorresponding one of the first and second carriers.

In this way, although the cam member is moved in the same way for eachuse, the indexing mechanism positions the carriers such that the pocketof one carrier is dispensed for a particular use of the cam member.Nevertheless, the same cam member is still able to open pockets fromeither of the carriers. Again, this is a highly efficient use of themechanism and also of space within the device.

Preferably, the cam member is moveable in a direction towards and awayfrom the second side surfaces of the supported first and second carrierssuch that, when the other of the first and second prodger members isaligned between respective pockets, movement of the cam member from therest position to the primed position and the resulting engagement of theother of the first and second prodger members with the corresponding camsurface causes the other of the first and second prodger members to abutthe corresponding second side surface and the cam member to be movedtowards the corresponding one of the first and second carriers.

Thus, for each use of the cam member, each cam surface pushes against acorresponding cam member. However, since one prodger member will abut asecond side surface between pockets and, therefore, will not itselfmove, the corresponding cam surface would actually cause the cam memberto move away from that second side surface.

In this way, in effect, both cam surfaces contribute to movement of aprodger member to open a pocket, such that each earn surface need haveonly a relatively small slope.

Preferably, the cam member is provided on a priming member moveable aspart of the indexing mechanism.

In this way, it is not necessary for a user to operate two separateactuators. Actuating the device to move the cam member in one directionwill prime the device so as to dispense a dose of powder for inhalationand then the movement of the cam member back to its rest position willindex at least one of the carriers ready for another pocket of powder tobe dispensed.

Preferably, the indexing mechanism is arranged such that, after thefirst and second carriers have been indexed past all of their respectivepockets, the first and second prodger members are both aligned betweenpockets of respective carriers and, hence, provide resistance tomovement of the cam member.

This provides a feature of “lock-out” whereby once all of the pockets ofthe carriers have been used and the device is effectively empty, theuser is provided with a physical feedback. In particular, it becomesdifficult for the user to move the priming lever of the device, sincethe cam member is unable to move the prodger members.

Preferably, the cam member includes an elongate flexible member havingfirst and second cam surfaces on opposite respective sides.

In this way, when it is required for the cam member or a portion of itto move from side to side, it is sufficient for only the elongateflexible member to move.

Preferably, the first cam surface and/or the second cam surface includesat least one groove into which any stray powder from previouslydispensed pockets may move.

In this way, stray powder will not interfere with the interface betweenthe cam surfaces and the prodger members such that operation will not beimpeded.

Preferably, the device is for use with carriers having the cavitiesformed from respective through holes between the first and second sidesurfaces, having second lidding sheets sealed to the second sidesurfaces and having respective cup shaped inserts in each cavityorientated with open portions facing the first lidding sheets, whereinthe first prodger member and/or second prodger member is arranged topenetrate an aligned through hole through a second lidding sheet so asto push the corresponding second insert outwardly through the firstlidding sheet.

This is a particularly effective way of dispensing doses of powder andthe mechanism for moving the prodgers is particularly effective inpushing the inserts as required.

Preferably, at least one of the cam surfaces is resiliently deformable,the cam member being dimensioned so as to move the prodger membersbeyond the extended position such that, once a prodger member reachesits respective extended position, further movement of the cam membercauses the at least one of the cam surfaces to resiliently deform.

In this way, the device can itself compensate for variations intolerances and it is not necessary for the cam member to move theprodger members by exactly the distance required.

Preferably, each support includes a peripheral array of gear teeth andthe indexing mechanism is engageable with the gear teeth so asselectively to move the supports and carriers.

This provides an advantageous way of moving and controlling thepositions of the carriers.

Preferably, the indexing mechanism includes a priming member mounted forrotation about a central axis and a Geneva wheel rotatably mounted on anaxis offset from the central axis for interaction with the primingmember and gear teeth of the supports such that rotation of the primingmember from a first position to a second position causes rotation of atleast one of the supports by a predetermined angle and rotation of thepriming member back from the second position to the first positioncauses no rotation of at least one of the supports.

Indeed, according to the present invention, there is also provided adevice for dispensing individual doses of powder from respective pocketsof a carrier, the device including a chassis, a first support mounted onthe chassis for rotation about a central axis and for supporting a firstcarrier having cavities with respective pockets formed therein andarranged in a circular array centred on the central axis, the firstsupport including an array of gear teeth centred on the central axis, apriming member mounted on the chassis for rotation about the centralaxis and an intermittent-motion mechanism mounted on the chassis forinteraction with the priming member and gear teeth of the first supportsuch that rotation of the priming member from a first position to asecond position causes rotation of the first support by a predeterminedangle and rotation of the priming member back from the second positionto the first position causes no rotation of the first support.

This allows a user to move the priming member through a relatively largeand imprecise range of movements whilst ensuring that the support andcarrier is moved by a predetermined amount.

Preferably, the intermittent-motion mechanism is a Geneva wheelrotatably mounted on the chassis on an axis offset from the centralaxis.

The device may further include a second support mounted on the chassisfor rotation about the central axis and for supporting a second carrierhaving cavities with respective pockets formed therein and arranged in acircular array centred on the central axis, the second support includingan array of gear teeth centred on the central axis wherein the Genevawheel may interact with the gear teeth of the second support such thatrotation of the priming member from the first position to the secondposition causes rotation of the second support by a predetermined angleand rotation of the priming member back from the second position to thefirst position causes no rotation of the second support.

In this way, the priming member may be used to rotate both the first andsecond supports and their associated carriers.

Preferably, the respective arrays of gear teeth of the first and secondsupports are incomplete circular arrays leaving respective spaces suchthat, with a space positioned between the Geneva wheel, rotation of thepriming member will not rotate the respective supports.

In this way, it is possible for the priming member to rotate selectivelyone or other of the supports.

The indexing mechanism may be actuated by a lever pivoted about the discaxis being moved through an angle between 30° and 180° and preferablythe indexing movement remains constant provided that the lever movesthrough a minimum angle.

The mechanism preferably locates to a radial accuracy sufficient toensure that the prodger member accurately locates on the pocket.Preferably, the force required to index the motion is between 1N and20N.

Preferably, the indexing mechanism holds the carriers in place so thatthey will not move when subjected to shocks such as experienced whencarried in the pocket or dropped onto a hard surface. It can be designedto index precisely between whatever number of pockets are on a disc.

The indexing mechanism preferably causes the selected disc carrier toincrement through a fixed angle to a deferred location so that theairway of the pocket that will be opened next is aligned to the airwayleading to the mouthpiece.

It is preferable that the priming lever used for indexing is not rigidlylinked to the position of the disc, as this would cause any smallmovement of the lever to disturb the alignment of the airways. Hence itis preferable that the correct motion of the disc occurs as the levermoves through the central part of its travel and that its start and endpositions are not critical to accurate operation.

Although various mechanisms could be used to achieve this type ofmotion, the preferred approach is to use a Geneva mechanism to allow thelost motion aspect of the indexing. A combination of gears with theGeneva mechanism can ensure that for every operation of the priminglever the carrier disc indexes a predetermined angle. For example, acarrier disc that has 31 positions would require an indexing angle of11.61 degrees.

Preferably, the device further includes a changeover component locatedbetween the first and second supports, the first support having a firstfeature engaging with the changeover component and the second supporthaving a second feature for engaging with the changeover component,wherein with the space of the second support adjacent the Geneva wheel,consecutive rotations of the priming member cause only the first supportto rotate until the first feature engages the changeover component andthen to move the changeover component so as to engage with the secondfeature and rotate the second support to a position with the space ofthe second support not adjacent the Geneva wheel, the space of the firstsupport then being adjacent the Geneva wheel and consecutive rotationsof the priming member causing only the second support to rotate.

In this way, it is possible to continuously operate the priming memberand yet achieve automatic changeover between indexing of the firstsupport and then the second support.

Preferably, the changeover component is arranged such that, when thepriming member rotates the second support back around to the positionwith the space of the second support adjacent the Geneva wheel, thesecond feature does not engage with the changeover component andconsecutive rotations of the priming member cause no rotation of eithersupport.

In this way, the device is automatically prevented from indexing topreviously used pockets of the carriers.

At this point in the operation, as described above, the first and secondprodger members are preferably both aligned between pockets ofrespective carriers and, hence, provide resistance to movement of thecam member. This provides the feature of “lock-out”.

According to the present invention, there is also provided a device fordispensing individual doses of powder from respective pockets of acarrier, the device including first and second supports rotatable abouta central axis and for supporting respective first arid second carriershaving cavities with respective pockets formed therein and arranged inrespective first and second circular arrays centred on the central axis,a changeover component located between the first and second supports,the first support having a first feature for engaging with thechangeover component and a second component having a second feature forengaging with the changeover component and an indexing mechanismarranged to rotate each of the first and second supports, wherein theindexing mechanism is arranged to rotate the first support until thefirst feature engages the changeover component such that the firstsupport then moves the changeover component, the changeover componentbeing arranged to then engage the second feature so as to rotate thesecond support to a position from which the indexing mechanism isarranged to rotate the second support.

In this way, a single indexing mechanism may be provided to rotate thefirst and second supports in sequence with changeover being achievedautomatically by means of the changeover component.

Preferably, the changeover component rotates to the second support froma position at which the indexing mechanism does not rotate the secondsupport and, when the first support moves the changeover component, thefirst support moves to a position which

the indexing mechanism does not rotate the first support.

When the second support is rotated back around to the position at whichthe indexing mechanism does not rotate the second support, consecutiveoperations of the indexing mechanism preferably cause no rotation ofeither support.

In this way, the device is automatically prevented from indexingcarriers to pockets which have already been used.

The changeover mechanism allows the same indexing mechanism to initiallyindex a first carrier disc and then, at a predetermined location, indexboth carrier discs together for one increment and then subsequentlycause the indexing mechanism to only index the second carrier disc.

The changeover action can be initiated solely by the angular position ofthe first carrier disc requiring no other input from the user andproviding insignificant difference in the tactile feedback.

Preferably, the changeover component is supported freely between and bythe first and second components.

Preferably, the device further includes a dose counter having a firstcounter ring having an indication of unit counts on a first displaysurface, the first counter ring being rotatable about a counter axis, asecond counter ring having an indication of tens counts on a seconddisplay surface, the second counter ring being rotatable about thecounter axis and a Geneva mechanism for driving the second counter ringfrom the first counter ring and rotating the second counter ring betweenconsecutive tens counts when the first counter ring rotates between twopredetermined unit counts.

In this way, the user is provided with an indication of the doses usedor the doses remaining.

By providing two counter rings respectively for units and tens,relatively large display figures may be provided, while still allowing alarge number of counts, for instance 40, 60 or 80. The Geneva mechanismprovides a particularly effective way of allowing the tens counter ringto be incremented as required.

Preferably, the first counter ring is driven with rotation of the firstsupport.

Hence, the count of unit doses dispensed is incremented/decrementedautomatically with each indexing of the device. The first counter ringmay include gear teeth around its outer periphery and an intermediategear may be provided to drive it from the indexing mechanism. Where, asdescribed above, the indexing mechanism includes a Geneva wheel, theintermediate gear can be driven directly from the Geneva wheel.

Preferably, the counter axis is coaxial with the first support.

Hence, the first and second counter rings may rotate about the same axisas the carriers and their supports. This allows a particularly compactarrangement.

According to the present invention, there may also be provided a devicefor dispensing individual doses of powder from respective pockets of acarrier, the device including an indexing mechanism for indexing thecarrier between respective pockets, a first counter ring having anindication of unit counts on a first display surface, the first counterring being rotatable about a counter axis, a second counter ring havingan indication of tens counts on a second display surface, the secondcounter ring being rotatable about the counter axis and anintermittent-motion mechanism for driving the second counter ring fromthe first counter ring and rotating the second counter ring betweenconsecutive tens counts where the first counter ring rotates between twopredetermined consecutive unit counts, the first counter ring beingdriven with the indexing mechanism.

Preferably, the intermittent-motion mechanism is a Geneva mechanism.

Hence, as described above, this allows a large number of counts to beprovided with relatively large display numerals.

Preferably, the first and second counter rings are positioned one withinthe other, with the first and second display surfaces adjacent eachother.

The display surfaces may thus be generally planar (and perpendicular tothe counter axis).

Preferably, the second counter ring may be positioned within the firstcounter ring, the first counter ring may include a pin for engaging aGeneva wheel rotatable about an axis offset from the counter axis andthe second counter ring may include features engageable by the Genevawheel.

In this way, during a complete revolution of the first counter ring, ata predetermined position of that revolution, a pin may engage the Genevawheel so as to rotate it and, hence, rotate the second counter wheel byone increment. This arrangement allows a particularly compact design.

According to the present invention, there is also provided a device fordispensing individual doses of powder from respective pockets of acarrier, the device including: an indexing mechanism for indexing thecarrier between respective pockets; a first counter ring having anindication of unit counts on a first display surface, the first counterring being rotatable about a counter axis; a second counter ring havingan indication of tens counts on a second display surface, the secondcounter ring being rotatable about the counter axis; and a mechanism forrotating the second counter ring between consecutive tens counts whenthe first counter ring rotates between two predetermined consecutiveunit counts, the first counter ring being driven with the indexingmechanism; wherein the first and second counter rings are positioned onewith the other, with the first and second display surfaces adjacent eachother.

It will be appreciated that devices according to the present inventioncan be provided with or without carriers.

The invention will be more clearly understood from the followingdescription, given by way of example only, with reference to theaccompanying drawings in which:

FIGS. 1( a) to (c) illustrate operation of an assembled device accordingto the present invention;

FIGS. 2( a) and 2(b) illustrate a carrier for use with the presentinvention without and with its lidding sheets;

FIGS. 3( a) and (b) illustrate movement of an insert from the carrier ofFIGS. 2( a) to (c);

FIGS. 4( a) and (b) illustrate a preferred arrangement for carrierswithin the device without and with supports of the device;

FIGS. 5( a) and (b) illustrate airway plates and anvil plates of thedevice in conjunction with corresponding carriers;

FIG. 6 illustrates an insert of a carrier pushed into its correspondinganvil plate;

FIGS. 7( a) and (b) illustrate movement of an insert of a carrier plateinto a corresponding anvil plate;

FIG. 8 illustrates the housing of the preferred embodiment;

FIG. 9 illustrates airflow paths through the preferred embodiment;

FIG. 10 illustrates the chassis and cam member assembly of the preferredembodiment;

FIG. 11 illustrates schematically operation of the dispensing mechanismof the preferred embodiment;

FIG. 12 illustrates schematically the preferred profile for the cammember;

FIG. 13 illustrates sub-assemblies of the preferred embodiment;

FIGS. 14( a) to (f) illustrate the Geneva mechanism of the indexingmechanism of an embodiment of the present invention;

FIGS. 15( a) to (e) illustrate the changeover mechanism of an embodimentof the present invention;

FIGS. 16( a) to (h) illustrate the dispensing mechanism of an embodimentof the present invention;

FIGS. 17( a) and (b) illustrate cross-sections through the components ofFIGS. 16( a) to (h);

FIG. 18 illustrates pockets being opened in a device embodying thepresent invention;

FIGS. 19( a) to (d) illustrate the Geneva mechanism of a counter in anembodiment of the present invention;

FIGS. 20( a) to (e) illustrate operation of the counter of FIGS. 19( a)to (d); and

FIGS. 21( a) and (b) illustrate preferred cross sectional areas atvarious locations in an embodiment of the present invention.

A preferred embodiment of the present invention is an inhalation devicefrom which a user may inhale consecutive doses of medicament in the formof dry powder. The preferred embodiment is illustrated in FIGS. 1( a) to(c).

The device includes a housing 2 on which a mouthpiece cover 4 isrotatably supported.

In order to use the device, the mouthpiece cover 4 is rotated away fromthe housing 2. As illustrated in FIG. 1( b) this exposes a mouthpiece 6.The mouthpiece 6 may be formed integrally with the housing 2, but, aswill be described below, it can also be formed as a separate componentfor mounting with the housing 2. This allows the material properties,for instance, colour, of the mouthpiece 6 and housing 2 to be variedeasily according to the requirements of the device.

As illustrated in FIG. 1( b), a priming lever 8 extends out of thehousing 2 at a position adjacent the mouthpiece 6. The priming lever 8is mounted so as to rotate about a central axis within the device (to bediscussed further below). In this way, it is moveable by the user arounda periphery of the housing 2 to a position as illustrated in FIG. 1( c).Movement of the priming lever 8 from the first position illustrated inFIG. 1( b) to the second position illustrated in FIG. 1( c) is arrangedto prime the device, in particular, to expose a dose of powder such thatit may be carried with an airstream out of the mouthpiece 6.

It should be noted that locating the first position of the priming lever8 adjacent the mouthpiece 6 is highly advantageous, since it discouragesa user from attempting to inhale from the mouthpiece 6 before moving thepriming lever 8 away from the mouthpiece 6 to the second position ofFIG. 1( c). In other words, the user is encouraged to prime the devicebefore attempting to inhale through it. Nevertheless, it should be notedthat a small space is preferably provided between the mouthpiece 6 andpriming lever 8 so as to allow the user to operate the priming lever 8with his or her finger without touching the mouthpiece 6.

After use of the device, the mouthpiece cover 4 may be rotated back toits stowed position illustrated in FIG. 1( a). In this respect, an innersurface of the mouthpiece cover 4 is provided with a return actuator forengaging with the priming lever 8. In particular, when the mouthpiececover 4 is moved from its open position of FIGS. 1( b) and (c) to itsclosed position of FIG. 1( a), the return actuator engages with thepriming lever 8 and moves it back from its second position illustratedin FIG. 1( c) to its first position illustrated in FIG. 1( b). As willbe described further below, in the preferred embodiment, this movementof the priming lever 8 operates an indexing mechanism for moving a stillunused and unopened pocket of powder into line with a dispensingmechanism such that, with subsequent priming of the device, the powderof that pocket is dispensed for inhalation. By operating the indexingmechanism during the return movement of the priming lever 8 immediatelyafter priming and release of a pocket of powder, if the released powderis not inhaled, it is indexed to a position where it can safely be heldwithin the device.

As illustrated in FIGS. 1( a) to (c), the preferred embodiment alsoincludes a window 10 in one side of the housing 2. The window 10 isprovided so as to allow a user to view a counter display within thedevice. A counter mechanism indexes the counter display upon each use ofthe device so as to provide the user with an indication of how may doseshave been dispensed and/or how may doses remain unused.

Many aspects of the present invention are applicable to devices housinga wide variety of different dose carriers. In particular, many of thefeatures of the embodiment described below can be used with carriershaving a traditional blister-pack construction, with carriers havingvarious arrays of pockets and, in some arrangements, with some carriershaving a single respective pocket. Nevertheless, the present inventionis particularly advantageous when used with carriers of the formillustrated in FIGS. 2( a) and (b).

As illustrated in FIG. 2( a), each carrier 12 is formed from adisc-shaped base 14 having a substantially planar first side surface 16opposite and parallel with a substantially planar second side surface18. A plurality of through holes 20 are formed between the first andsecond side surfaces 16, 18 so as to form spaces for housing doses ofpowder. The base 14 is formed with an appreciable thickness so as toprovide the through holes 20 with sufficient space to house the requireddoses of powder. The through boles 20 are arranged as a circumferentialarray and, in the preferred embodiment, 30 through holes are provided inthe array.

As illustrated in FIG. 2( b), the first and second side surfaces 16, 18of the base 14 are sealed with respective first and second liddingsheets 22, 24. In this way, the carrier 12 provides a plurality ofpockets housing individual respective doses of powder.

As illustrated by the cross-sections of FIGS. 3( a) and (b), the pocketspreferably include a respective insert 26 within each through hole 20.The inserts 26 are generally cup-shaped with their open ends facing thefirst lidding sheet 22. Each contain a respective dose of powder 28.

By pushing on the closed end of the insert 26 from the side of thesecond lidding sheet 24, it is possible to push the insert 26 outwardlyfrom the base 14 of the carrier 12 through the first lidding sheet 22.This is illustrated in FIG. 3( b), but, for clarity, without eitherlidding sheet. As illustrated, with the insert 26 extending out of thebase 14, it may be more convenient to provide an airflow (such asindicated by arrows) to remove powder from the pocket.

Within the housing 2 of the inhalation device, in a preferredembodiment, two of the carriers 12 are arranged coaxially side by sideas illustrated in FIG. 4( a). Each carrier 12 is provided with a support30 as illustrated in FIG. 4( b). In the illustrated embodiment, eachsupport 30 is positioned adjacent an outwardly facing surface of itsrespective carrier 12. In particular, the first side surface 16 of eachcarrier 12 faces a respective support 30 such that a dispensingmechanism may be provided between the two carriers 12 so as to pressrespective inserts 26 outwardly towards the respective supports 30. Thepreferred arrangement for this will be described further below.

As illustrated, the priming lever 8 is positioned such that it extendsbetween the carriers 12 and is rotatable about the common axis of thecarriers 12 so as to operate a dispensing mechanism and an indexingmechanism.

In the preferred embodiment, each support 30 is made up of twocomponents, namely an anvil plate 32 and an airway plate 34. These areillustrated in FIGS. 5( a) and (b) in conjunction with associatedcarriers 12.

Each anvil plate 32 has a planar surface 36 which; in use, abuts againstthe first side surface 16 of the associated carrier 12 as covered by thefirst lidding sheet 22. Each anvil plate 32 also includes a plurality ofguide through holes 38 corresponding to the through holes 20 of theassociated carrier 12.

In this way, as illustrated schematically in FIG. 6, an insert 26 can bepushed out of its through hole 20 and into a corresponding guide throughhole 38 of the anvil plate 32. The insert 26 is thus used to outwardlyburst through the first lidding sheet 22, but is still held securely inplace. Although not of a particular concern here, the anvil plate 32also supports the first lidding sheet 22 around the through hole 20 andcan be used to improve the predictability of the nature of the liddingsheet rupture.

As illustrated by the cross-section of FIG. 7( a), the anvil plate 32includes a second surface 40 which abuts an inner surface of theassociated airway plate 34. The airway plate 34 includes a pair ofthrough holes corresponding to each guide through hole 38 of thecorresponding anvil plate 32. In particular, each pair includes an inlethole 42 and an outlet hole 44.

As illustrated in FIG. 7( a), relative to the surface 40 of the anvilplate 32 abutting the inner surface of the airway plate 34, a recessedchannel 46 extends radially inwardly from the outlet 44 so as tocommunicate with the guide through-hole 38 of the anvil plate 32. Hence,for each guide through hole 38 of the anvil plate 32, the airway plate34 provides, communicating with it, a corresponding inlet 42 and outlet44 with its associated recessed channel 46. In particular, each inlet 42communicates with one side of its associated guide through hole 38whilst the corresponding outlet 44 communicates with the opposite sideof the associated guide through hole 38.

As illustrated in FIG. 7( b), when an insert 26 is pushed outwardly ofthe through hole 20 of the base 14 into the guide through hole 38 of theanvil plate 32, it is positioned with the open portion of its cup-shapefacing the inlet 42 (at one end of the cup-shape) and the recessedchannel 46 (at the opposite end of the cup-shape). In this way, asillustrated, an airflow may be drawn through the airway plate 34 suchthat it passes down into the pocket formed in the insert 26, back upinto the recessed channel 46 and then out of the outlet 44. Powder inthe insert 26 is thus picked up by the airstream, removed from theinsert 26 and carried out of the airway plate 34. A flow path is thusformed into and out of a pocket which may then connect the pocket to themouthpiece 6 of the device.

As illustrated in FIG. 8, the housing 2 may be formed from a pair ofcasing halves 2 a and 2 b. As illustrated in FIGS. 9( a) and (b), aninner wall 50 of the casing halves 2 a and 2 b cooperates with theairway plate 34 so as to form a second flow path to the mouthpiece 6which bypasses the pocket(s). Alternatively, an additional component maybe provided to define the second flow path.

As illustrated in FIG. 9( b), for each pocket formed by an insert 26,the corresponding inlet 42 of the airway plate 34 is positioned adjacenta periphery of the pocket. The corresponding outlet 44 is provided on anopposite side of the pocket such that the airstream between the inlet 42and outlet 44 crosses the pocket and, hence, picks up any powder fromthe packet.

As illustrated, the inlet 42 is formed as a portion which is directeddown into the insert 26 forming the pocket.

In this way, when a user inhales through the device and creates anairstream through it, the airstream drawn through the inlet 42 will bedirected down into any powder in the insert 26 so as to dislodge it andmove it into the airstream so as to be carried out of the outlet 44. Inthe illustrated embodiment, the recessed channel 46, which connects thevolume of the pocket to the outlet 44, is positioned adjacent the inlet42. In this way, the airstream from the inlet 42 is deflected from thebase of the insert 26 (and any powder there) so as to travel backtowards the recessed channel 46. Powder carried in the airstream up intothe recessed channel 46 is subjected to a relatively sharp change indirection. As a result of this, powder in the airstream tends to bedeaggregated. Furthermore, the powder will tend to hit the surfaces ofthe recessed channel 46 also contributing to deaggregation.

As is clear from FIG. 9( b), the shape of the airway path is chosen toforce large aggregates of powder to impact the walls as the airflow isforced to change direction, thereby deaggregating large clumps ofpowder. The shape is also designed to ensure that airflow over anysurface within the airway is maintained at a high value to avoidexcessive powder adhering to the surface. Thus corners are rounded andthe cross section at each position along the tube is designed tomaintain air velocity without generating excessive pressure drop.

As illustrated in FIG. 9( a), in this embodiment, the airflow throughthe pocket has its minimum area at the inlet to the pocket defined bythe dimension “a” whereas the airflow that bypasses the pocket has itsminimum cross section just before the airflow join and so is defined bythe dimension A.

The air velocity is highest where the cross sectional area is smallestso this arrangement provides high velocity air to extract the powderfrom the pocket and uses the high velocity of the bypass air joining thepowder contained in the pocket airflow to assist de-aggregation and toprotect the walls from powder deposition.

The airflow velocity through the pocket is controlled mainly by thesuction pressure created as the user inhales, whereas the volume flowrate is a factor of both velocity and area.

A sufficiently high air velocity should be generated to ensure that thepowder is entrained in the airflow. However, if the velocity and flowvolume are too high then there is the possibility that the whole of themass of powder in the pocket is pushed through the airway as anagglomerated clump. If this happens, the clump may not accelerate to asufficient velocity for its impact with the walls in the airway to breakit up and provide de-aggregation. It is preferred that the powder isremoved gradually from the pocket by the airflow. To achieve this, asmall gap 46 a is provided between the surface of the powder in thepocket and the airway roof formed from the division in the airway plate34 between the inlet 42 and recessed channel 46. This, combined with adimension for “a” that limits the flow volume through the pocket,ensures that the powder is eroded from the pocket rather than pushedout.

To enable this, the inlet hole diameter “a” is chosen to be between 0.5mm and 2.0 mm for pockets of around 2.0 mm width (in a circumferentialdirection) and of around 7.3 mm length (in a radial direction). Thevalue chosen depends on the properties of the powder.

In this way, the powder can be removed from the pocket over a timeperiod ranging from between 0.1 s to 1.0 s. This is within the period ofthe high flow rate of the inhalation cycle and provides goodde-aggregation of the powder.

It should be appreciated that, in other embodiments, it is possible forparts of the flow path through the pocket, other than the inlet hole,for instance downstream of the powder, to form the minimumcross-sectional area of that flow path. Similar considerations willstill apply for the diameter “a” of the inlet hole.

The arrangement of the inlet hole 42 and channel 46 is particularlyadvantageous in conjunction with deep narrow pockets of powder. At aparticular flow rate, for instance 10 ltr/min, the surface of the powderwill be eroded by a certain depth. Increasing the flow rate to, forinstance 20 ltr/min, will result in the powder being eroded by a furtherdepth. Since inhalation by users results in flow rates which increaseprogressively to a maximum, powder is eroded depth by depth and thepocket is emptied gradually over an appropriate period.

Although the volume and strength of inhalation will vary between users,it is important that the device should not provide too much in the wayof resistance to inhalation. In this respect, it would be extremelydifficult to inhale through an inlet 42 having a desired cross sectionalarea. Indeed, where possible, it would result in a flow velocity whichwas far too high and which would entrain of all of the powder from theinsert 26 far too quickly. In practice, it is found that approximatelyonly 20% of inhaled air can be used directly for picking up anddeaggregating the powder.

As illustrated in FIG. 9( b), a second flow path is formed between aninner wall 50 of the housing 2 and the outside of the airway plate 34.The second flow path bypasses the pocket and increases the overall crosssectional area available through which to inhale. By changing the valuesof the dimensions a and A, it is possible to change the rates of airflowbetween the pocket and bypass and to control the overall flow resistanceof the device so that it is comfortable for the user to inhale through.A typical flow resistance for the device would be between 2 kPa and 5Kpa for a flow volume of 60 l/min. Higher flow resistances are chosenfor powders which are harder to deaggregate, whereas lower flowresistances are preferred for devices used by children. The recessedchannel 46 and outlet 44 generally have larger cross sectional areasthan the inlet 42. It is envisaged that the minimum cross sectional areafor the pocket path would be 3.5 mm² to 4.0 mm² and for the bypass 5.0mm² to 6.0 mm².

In this way, it is relatively easy to inhale through the device, since alarge proportion of the airflow will be through the second flow path.Nevertheless, some of the flow will occur through the first flow path soas to entrain and deaggregate the powder as described above.

In the preferred embodiment, there is another second flow path for theother side of the device and its corresponding carrier. In use, apatient inhales through both second flow paths whilst drawing powderfrom the first flow path in use. Each of the second flow paths isexpected to carry approximately 40% of the total inhaled air for anaverage use.

Actual requirements will vary depending upon the nature of the powderand the intended user. For an easily dispensed powder, the portionforming the inlet to the pocket can be small and, for a child or patientwith COPD (Chronic Obstructive Pulmonary Disease), the total pressuredrop should be low. In this case, an inlet portion could be providedwith a cross-sectional area of 2 mm² and a bypass second flow path witha minimum cross-sectional area of 8 mm², resulting in a ratio of 25%. Onthe other hand, with sticky powder for a healthy adult, the inletportion could be provided with a cross-sectional area of 4 mm² togetherwith a bypass second flow path having a minimum cross-sectional area of6 mm², resulting in a ratio of 66%. Of course, intermediate values arealso possible and a preferred arrangement has an inlet portion ofapproximately 3 mm² with a second flow path minimum cross-sectional areaof 6 mm², resulting in a ratio of 50%.

As illustrated in FIG. 9( a), the walls of the outlet 44 are orientatedso as to direct the flow of air and powder into the second flow path atan angle θ relative to the flow in the second flow path. By ensuringthat the angle θ is less than 45°, it is possible to substantiallyreduce the amount of powder which might impact with or stick to the wall50 opposite the outlet 44. Preferably the angle θ is no greater than45°, more preferably no greater than 30°. In this way, substantially nopowder will adhere to the wall 50 forming the second flow path to themouthpiece 6. Preferably, with repeated use of the device, no more than25%, preferably no more than 15% of a dose remains deposited on the wall50. In this respect, it will be appreciated that the flow from thebypass past wall 50 will act to scour or scavenge powder from the wall50.

As mentioned above with reference to FIG. 4( b), the anvil plate 32 andairway plate 34 together form a support for a corresponding carrier 12.By means of the priming lever 8 and the indexing mechanism to bedescribed below, a support 30 and its corresponding carrier 12 is movedto consecutive positions to dispense powder from consecutive pockets. Inthis regard, it will be appreciated that each pocket has its own firstflow path as formed in the airway plate 34. From the description above,it will be appreciated that turbulent flow in removing powder from thepocket and deaggregation of powder occurs within the first flow path.Thus, should any powder adhere to walls within the airway plate 34, thispowder is not available for inhalation when subsequent pockets of powderare dispensed.

The device is preferably arranged such that an inlet passage thatprovides the air for the flow through the pocket and through the bypassis arranged so that it feeds the air only to the pocket positioned fordispensing, such as illustrated in FIGS. 9( a) and (b). The indexing ofthe carrier 12, anvil plate 32 and airway plate 34 after use repositionsthe inlet 42 and outlet 44 for a used pocket outside of the airflow forthe pocket currently in use.

This arrangement ensures that, even if none of the powder from a pocketis removed after it has been opened, once it has been indexed on, thenthe powder will be permanently retained within the device such that itwill not be inhaled along with a subsequent dose.

The supports 30 and associated carriers 12 may be rotatably mountedwithin the housing 2 by means of a chassis sub-assembly 58 asillustrated in FIG. 10. The chassis sub-assembly 58 is positionedbetween the second side surfaces 18 of the carriers 12. It extendsaxially along the axis of the carriers 12 and is fixed to one or both ofthe two halves 2 a, 2 b of the housing 2.

As illustrated in FIG. 10, the priming lever 8 forms part of (or couldbe attached to) a priming member 60. The priming member 60 has a centralpivot opening 62 by which it is rotatably supported on a pivot shaft 64of a chassis 66.

As illustrated in FIG. 13, the priming member 60 and chassis 66 aretogether positioned between the two carriers 12 and associated supports30. Furthermore, the chassis 66 is mounted to the housing 2 so as to berotatably fixed. In the illustrated embodiment, the pivot shaft 64 mayitself be located on a shaft 68 provided on the inside of one or bothhalves 2 a, 2 b of the housing 2. Also, a radial extension 70 (shown inFIG. 10) may be provided on the chassis 66 to interact with an innerportion of the housing 2 so as to rotationally fix the chassis 66.

The carriers 12 and associated supports 30 may be rotationally mountedon the chassis 66.

The priming member 60 includes an elongate cam member 72 which extendsin a circumferential direction and has a cam surface 74 on each of twoopposites sides.

Each cam surface 74 interacts with a respective member 76 which will bedescribed as a prodger.

Operation of the priming member 60, cam member 72, cam surfaces 74 andprodgers 76 will be described with reference to the schematicillustration of FIG. 11.

When the priming lever 8 is moved from its first position to its secondposition, the priming member 60 is rotated relative to the chassis 66,the carriers 12 and their supports 30 such that, in the schematicillustration FIG. 11, the cam member 72 moves upwardly.

As can be seen in FIG. 10, the priming member 60 includes elongateopenings either side of the cam member 72 through which arms 80 of theprodgers 76 can extend. The chassis 66 holds the prodger 76 rotationallybut allows them to move in an axial direction of the device, in otherwords towards and away from the carriers 12 on either side. Indeed, asillustrated, an aperture 82 exists in the chassis 66 allowing one of theprodgers 76 to extend through the chassis 66 towards a correspondingcarrier 12.

As illustrated in FIG. 11, the cam surface 74 on either side of the cammember 72 is such that, as the priming member 60 rotates and the cammember 72 moves upwardly as illustrated in FIG. 11, the prodgers 76 aremoved outwardly towards their respective carriers 12.

In FIG. 11, the right hand prodger 76 is illustrated in alignment with apocket in its corresponding carrier 12. Thus, when the priming member 60rotates and the cam member 72 moves upwardly in FIG. 11, the right handprodger 76 will be moved outwardly towards its corresponding carrier 12,will penetrate the through hole 20 and push the insert 26 a out of thefirst side surface 16. In this respect, FIG. 11 illustrates one insert26 b which has already been pushed out by the prodger 76.

An indexing mechanism, to be described below, rotates the right handcarrier 12 and its corresponding support 30 to the next position inwhich the prodger 76 is aligned with

a new unopened pocket. The operation of opening a pocket can then berepeated.

It will be appreciated from FIG. 11 that carriers 12 on either side ofthe priming member 60 could have respective pockets aligned with theprodgers 76 such that operation of the cam member 72 simultaneouslyopens pockets of the respective carriers 12. However, in the illustratedembodiment, the indexing mechanism arranges for one of the prodgers 76to be aligned with a pocket whilst the other of the prodgers 76 is at aposition between pockets. In this way, the dispensing mechanism formedfrom the cam member 72 and prodgers 76 only opens one pocket at a time.

Referring to FIG. 2( a), it will be seen that the preferred carrier 12has an array of through holes 20 which includes a space 82 in which athrough hole 20 is not formed.

Using carriers of this type, it is possible to position one carrier 12with the blank portion 82 opposite a prodger 76 whilst consecutivelyindexing the other carrier 12 around each of its through holes 20 andthe pockets they form until all have been emptied. The indexingmechanism can then rotate the empty carrier to a position in which itsblank portion 82 is opposite the prodger 76 and rotate the other carrier12 around all of the positions in which the corresponding prodger 76aligns with the through holes 20. In this way, the same dispensingmechanism is used for dispensing powder from both carriers and using thesame operation.

Although it is the intention that substantially all of the powderdispensed from the individual pockets will be removed from the device byway of inhalation, it is possible that some powder will remain withinthe device. Indeed, where different types of carrier are used or thedevice has a different application, it might be that more powder doesremain within the device.

As illustrated in FIG. 10, the cam surfaces 74 are provided with one ormore grooves or channels 84. Any excess powder can thus fall into thegrooves 84 such that contact and movement between the cam surface 74 andthe prodger 76 is not impeded.

It will be appreciated that, with the arrangement where one or other ofthe prodgers 76 abuts a portion 82 of a carrier 12 where there is nopocket, in order for the priming member 60 to rotate and the cam member72 to move a prodger 76 towards the other carrier 12, it will benecessary for the cam member 72 to move away from the portion 82. Insome embodiments, it might be possible to allow the entire primingmember 60 to move axially or for the carriers 12 to move axially.However, in the preferred embodiment, the cam member 72 has itself alimited amount of flexibility. As illustrated, the cam member 72 isprovided as an elongate member which is attached to the rest of thepriming member 60 at each end with an elongate opening either side ofit. This will allow sufficient flexibility for the cam member 72 to movetowards and away from the carriers 12.

Considering the overall embodiment as described with reference to FIG.1( a) to (c), it will be appreciated that it is highly desirable toensure that the user moves the priming lever 8 through its entire lengthof travel so as to fully dispense a dose of powder. In particular,considering FIG. 11, it would be undesirable for a user to partlyoperate the priming lever 8 and priming member 60 such that a prodger 76pushes an insert 26 far enough to partly rupture a lidding sheet on thefirst side surface 16, but without fully extending the insert 26 to theposition illustrated in FIGS. 6 and 7( b).

As the motion of the inserts 26 is restricted by the foils 22, 24sealing both surfaces of the carrier plate 12, a high force is requiredto cause the inserts 26 to start to move. This force increases to thepoint at which the foils 22, 24 rupture after which the force decreasessubstantially. Thus, the user feels a resistance to the motion of thepriming lever 8 for the early part of its travel. At some point alongits travel, the resistance suddenly reduces, as the foil 22, 24 rupture.The user cannot reduce the applied force instantaneously so that thepriming lever 8 is rapidly pushed to the end of its available stroke.This tactile feedback encourages the user to fully open the pockets.

If the cam member 72 driving the prodgers 76 was solid as shown in FIG.11, then the inserts 26 would be forced to the positions shown. However,in the preferred embodiment where the parts are moulded in plastic, itis impossible to control the dimensions of all parts with absoluteaccuracy. Thus, where the distance moved by the insert 26 is smallerthan the space allowed for it, there would be a gap above the pocket butwhere the distance moved is greater than the distance allowed for it,the anvil plates 32 would be pushed apart from the carriers 12 by theforce. This force would be transmitted to the casework causing it todeform if sufficiently high force was applied to the priming lever 8.

To avoid this potential problem, the cam member 72 is made to a formthat varies its force versus distance profile along its length.

An example of a suitable form is shown in FIG. 12. The preferredembodiment includes two such members arranged back to back. The solidwedge shape profile at the right hand side as illustrated in FIG. 12 hasthe same profile as shown in FIG. 11. This form rigidly transmits theforce applied by the priming lever 8 to the insert 26. The length ofthis profile is chosen so that, for all devices, the prodgers 76 will bemoved sufficiently far to break the foils 22, 24 by this profile. Oncethe foils 22, 24 are broken, much less force is required, but thedistance that the insert 26 must move may vary from device to device.Thus, for the last part of its travel, the cam member 72 cross-sectionis designed to provide compliance in its movement. This ensures that thecam member 72 provides sufficient force for the insert 26 to be pushedto the end of its available travel in the anvil plate 32. However, afterthe insert 26 is stopped at the end of its travel, the force that thecam member 72 applies to the prodger 76 is limited to that generated asit deforms. This can be much less than the force that would be appliedif the prodger 76 were rigidly connected to the priming member 60.

In this way, reliable opening of the pocket is achieved using componentsthat can be manufactured using conventional materials and mouldingprocesses.

The action of cam member 72 and prodger 76 is further illustrated inFIGS. 16( a) to 16(h). These Figures show the cam member 72 and prodger76 at sequential positions as the priming lever 8 and priming member 60are moved to open a pocket. The Figures are grouped in pairs, each groupgiving two views of the same position.

FIGS. 16( a) and 16(b) show the prodger 76 a in its fully retractedposition at one end of the cam member 72. The prodgers 76 a and 76 b areidentical components that clip together with the cam member 72 betweenthem. Each prodger 76 has features 86 at the ends of their arms 80 thatlocate with additional cam surfaces 88 formed on the priming member 60either side of the elongate openings though which the arms 80 extend.

Where a prodger member 76 has penetrated past the first surface of acarrier disc in order to push the pocket through the second surface,then it is necessary to retract the prodger member 76 before the carrierdisc can be indexed to its next position.

A spring could be used to achieve this if it were positioned to pressthe prodger member 76 against its base surface. However, it ispreferable to have an active method for retracting the prodger member 76that acts as the cam member 72 is returned to the original position.However, where the action of returning the cam member 72 to its originalposition is also used to index the carrier disc, it is important toensure that the retraction of the prodger members 76 is completed beforethe carrier disc is indexed.

A preferred method of achieving this is by the use of the further camsurfaces 88 located in the non-moving housing in which the cam memberand carrier discs are located.

FIG. 17( a) shows a schematic cross section through the prodgers 76 aand 76 b also in their retracted position.

The location of prodger 76 a is constrained by the surface 90 of the cam88 and the earn surface 74 of the cam member 72. The cams 88 and cammember 72 are designed so that their thickness C1 and C2 change alongthe direction of the primary member 60 motion. FIG. 17( b) shows theprodgers 76 a and 76 b in their open position where it can be seen thatC2 has increased and C1 decreased compared to their values at the closedposition.

The cam member 72 has a rectangular cross section C2 at one end thatgradually increases in area. At the point that it starts to become acompliant wedge, rather than a rigid one, the wedge splits into acentral part that pushes up 74 and two side parts that push down 74 a.

This arrangement provides a positive force to both open and close theprodgers 76 a and 76 b.

FIGS. 16( c) to 16(h) show how the concept illustrated in FIGS. 17( a)and (b) might be implemented.

FIGS. 16( c) and (d) show the prodgers 76 a and 76 b where the cammember 72 has completed approximately one third of its full travel. Thecam member 72 over this section is of uniform thickness such that theprodgers are fully retracted. This allows the movement of the rotarypriming member 60 on the return stroke over this section to drive theindexing mechanism (as will be described below).

FIGS. 16( e) and (f) show the prodgers 76 a and 76 b where the cammember 72 has completed two thirds of its travel. The cam member 72along this section includes the circumferential grooves 84 mentionedabove. The raised parts of the cam member 72 are sufficient to rigidlycouple the force applied to the priming lever 8 to the prodgers 76 a and76 b and the grooves 84 are provided solely to increase the tolerance ofthe mechanism to stray powder that may have collected on the cam surface74.

FIGS. 16( g) and (h) show the prodger where the cam member 72 hascompleted its travel. In this section, the cam member 72 is not solidbut split into a central section and two side sections arranged so thatthe central section presses up against one prodger whilst the two outersections press down against the other prodger.

If the prodgers 76 a and 76 b reach the end of their travel before thecam member 72 reaches the end of its travel, then the thinned section ofthe cam member 72 at this point will be deflected, thereby limiting theforce applied to the prodgers 76 a and 76 b over the remaining travel ofthe cam member 72.

In the preferred embodiment, the indexing of the two carrier assemblies(FIGS. 5( a) and (b)) is accomplished by an indexing mechanism thatcauses a carrier 12 to be incremented by one pocket each time thepriming lever 8 is actuated and a changeover mechanism that causes theindexing mechanism initially to drive the first carrier 12 but, when thelast pocket of that carrier 12 has been used, for that carrier 12 toremain stationery whilst the second carrier 12 is incremented when theindexing mechanism is actuated.

The preferred indexing mechanism illustrated in FIGS. 14( a) to (f) usesa 3 peg Geneva 100 that rotates exactly 120° each time the indexingmechanism is actuated. The Geneva peg wheel 100 has two gears co-axialwith the peg-wheel arranged so that the gears can engage with teeth 35on the airway plates 34.

To avoid having both airway plates 34 driven simultaneously, it isarranged that, at one location around the airway plate 34, the gearteeth 35 are missing. As a result, at this location, rotation of theGeneva peg wheel 100 does not rotate the airway plate 34. Thus, theindexing mechanism drives the first carrier 12 via the Geneva 100 andits gears until it reaches the end of the gear teeth 35 for that carrier12. The next indexing moves the first carrier 12 to its non-drivenposition, i.e. where the gear teeth 35 are missing, and engages achangeover mechanism which rotates the second carrier 12 until its gears35 are engaged with the gears on the Geneva peg wheel 100.

A preferred embodiment of the indexing mechanism is illustrated in FIGS.14( a) to 14(f). In these, it can be seen that the peg wheel 100 islocated with its axis parallel to the axis of the dose carriers 12 androtary priming member 60.

The rotary priming member 60 incorporates many of the functionalelements described previously within a single moulded component. Itincludes the priming lever 8, the cam member 72 and the prodger closingcams 83, as well as being the driving member for the indexing Geneva100.

The Figures start with the priming member 60 at the end of its travelwhere a pocket has been opened and shows what happens as the priminglever 8 is returned to its start position by the closing of themouthpiece cover 4.

The peg wheel 100 has six pegs 102 a-102 c, 103 a-103 c arranged at 60°intervals around its edge. Three of these pegs 102 a, 102 b; 102 c arelonger than the other three 103 a, 103 b, 103 c and are shown with blackends for clarity. As the rotary priming member 60 moves from itsposition in FIG. 14( a) to that in FIG. 14( b), the leading part 101 ofa driving member 104 formed by the priming member 60 passes over theshort peg 103 a with its periphery touching the edges of the longer pegs102 a and 102 c preventing the peg wheel 100 from rotating. At theposition shown in FIG. 14( b), a ratchet 105, which slopes downward andforward from the driving member 104, engages with the peg 103 a. As thepriming member 60 and the driving member 104 continue to move from theposition of FIG. 14( b) to that of FIG. 14( c), the peg wheel is drivenaround. To permit the peg wheel 100 to rotate, a slot 106 is cut intothe driving member 104 of the priming member 60 into which the long peg102 c can enter. At the position of FIG. 14( c), the ratchet 105 isstarting to disengage with the peg 103 a but the trailing edge 107 ofthe slot 106 now engages with the long peg 102 c and continues to drivethe peg-wheel 100 around through to the position shown in FIG. 14( d).At the position of FIG. 14( d), the edge 108 of the driving member 104passes over the short peg 103 c. The peg wheel 100 then continues torotate to the position of FIG. 14( e) to complete the forward motion ofthe peg wheel 100. The slot 109 is provided to accommodate the long peg102 b. At this position, the dose carrier 12 has been driven so that thenext pocket to be opened is beyond its desired location and themouthpiece cover 4 that has been driving the rotary priming member 60 isfully closed.

When the priming lever 8 is pushed in the reverse direction by the userto open a pocket, the initial part of the travel, over which theprodgers 76 a and 76 b are not moved, takes the rotary priming member 60plate back from the position shown in FIG. 14( e) to that shown in FIG.14( b). The angled face 110 in the slot 109 on the rotary priming member60 pushes on the long peg 102 b causing the peg wheel 100 to rotatebackwards until the two long pegs 102 b and 102 c are both dis-engagedfrom the driving edges and pressing against the outer periphery 108 ofthe rotary priming member 60.

This accurately defines the rotary position of the peg wheel 100,ensuring that the prodgers 76 a and 76 b accurately line up with thepockets. The short peg 103 c, that is within the outer periphery of therotary priming member 60, is short enough to allow the ratchet 105 toreturn over the top of it. Thus, after the initial movement, the pegwheel 100 is held stationary throughout the remainder of the strokeopening a pocket. Thus, each indexing operation causes the peg wheel 100to rotate 120°. The gears above and below the plane of the peg wheel 100are shown in FIG. 14( f) which for clarity is viewed from the oppositeside from FIGS. 14( a) to 14(e). FIG. 14( f) shows the gears 35 on oneof the airway plates 34 engaged with the gear on the peg wheel 100. Thenumber of gear teeth on the airway plates 34 and peg wheel 100 arearranged so that the 120° motion of the peg wheel increments the dosecarrier plate exactly one pocket pitch.

The arrangement described here is advantageous in achieving preciseintermittent motion control of two disks within very tight spaceallocation and with a minimal number of components.

As described previously, for the device to operate with two disk carrierplates, a changeover mechanism is preferably provided to cause theindexing mechanism initially to drive a first disk and, when this hashad all of its pockets opened, to then drive a second disk. Such achangeover mechanism will be described with reference to FIG. 15( a) toFIG. 15( e). These Figures show the device viewed edge on with the twoairway plates 34 arranged horizontally.

FIG. 15( a) shows the device in its position before a first pocket isopened.

In FIG. 15( b), airway plate 34 a has been indexed by one position tothe right. The two features 123 on the periphery of the airway plate 34a can be seen to have shifted.

FIG. 15( c) shows the position after the last pocket of the lowercarrier 12 of airway plate 34 a has been opened. The rotation hasbrought the features 123 right around the device to the position shown.The next indexing operation causes the lower airway plate 34 a to moveas before. However, the leading feature 123 pushes on a changeovercomponent 124 which pushes on the feature 122 on the upper airway plate34 b causing both plates 34 a and 34 b and carriers 12 to move together.When the upper airway plate 34 b was in its original position, theprodger 76 b was aligned to the missing pocket part 82 providing a hardsurface against which that prodger 76 b could push whilst the otherprodger 76 a pushed against a pocket of the lower airway plate 34 a. Inaddition, at this location, the missing teeth on the gear 35 of theupper airway plate 34 b aligned with the gear on the Geneva peg wheel100 and, hence, rotation of the peg wheel 100 did not index the upperairway plate 34 b. However, the indexing operation performed by thechangeover component 124 on the upper airway plate 34 b moves the gearof the upper airway plate 34 b to engage with the gear of the peg wheel100 and aligns the first pocket of the upper carrier 12 with theprodgers 76. Simultaneously, indexing by the priming member 60 causesthe lower airway plate 34 a to continue to move to a position which thegear teeth 35 on the lower airway plate 34 a disengage from the gear onthe peg wheel 100. The priming member 60 and peg wheel 100 move thelower airway plate 34 a to a position in which the missing teeth on thegear 35 of the lower airway plate 34 a are aligned with the gear on theGeneva peg wheel 100 and the missing pocket segment 82 of the lower dosecarrier 12 is aligned with the prodgers 76.

The clip 125 provides an interlock that prevents any frictional couplingfrom causing the upper airway plate 34 b to move before the lower airwayplate 34 a has arrived at the correct location.

Thus, changeover from the indexing of one disc to the other is achievedautomatically and with minimal number of components and in a very smallspace.

The indexing of the device, in addition to moving the next pocket intoalignment with the prodgers 76, preferably actuates a dose counter thatprovides a visual indication to the user of the number of dosesremaining. The operation of the dose indicator will be described withreference to FIGS. 19 and 20.

It is preferable that the device, when dispensing medicament, indicatesto the user the number of doses remaining in the device.

It is preferable that such indication is easily readable and, as such,very small numbers indicating the remaining doses would be adisadvantage. Within the size constraints of a pocket portable devicethat contains 60 doses providing such a display is challenging.

The simplest arrangement of marking the carrier discs with numbersvisible through windows in the casework requires, where two carrierdiscs are used, the user to view different windows and, in addition, thespace available around the carrier disc means that the size of thenumbers would be small.

A preferred method is to employ a display with separate units and tensindication, driven such that the tens display index one number as theunit display index from 9 to 0. This allows larger numbers to be usedwithin the same casework. The two discs may be provided concentricallyone within the other and preferably coaxially with the axis of thedevice, for instance on the shaft 68 illustrated in FIG. 13. Thedisplayed units and tens are visible through the window 10 illustratedin FIG. 1( a).

In a preferred embodiment, the display counts down to zero, but the tensdisc is not provided with a “0”. Instead, it is provided with anindicator, for instance a symbol, colour light etc to indicate to theuser that the device is nearing the end of its functional life.

The preferred embodiment uses another Geneva and gear arrangement thatis driven from the movement of the carrier discs. It is preferable thata single counter is increment initially by the motion of the firstcarrier disc and subsequently by the motion of the second carrier discsuch that the fact that the device contains two carrier discs is notapparent to the user.

FIG. 20( a) shows a view of the dose counter display. The counterconsists of two concentric rings 130, 131 with numbers formed in therings facing toward the outer casing 2 of the device. The outer ring isthe units counter 130 and the inner ring is the tens counter 131. Thewindow 10 is provided in the outer casework 2 is arranged to permit theuser to see only one digit of the units counter 130 and the adjacentdigit of the tens counter 131. In FIG. 20( a), the counter indicatesthat there are 21 doses left. The operation of the counter requires theunits counter 130 to index by 36° every time the indexing mechanism isactuated and for the tens counter to index by 36° only as the unitscounter moves from displaying 9 to 0. It can be seen that the unitsdigits are evenly distributed around the ring whereas, for the exampleshown in FIG. 20( a) which has 60 doses, there are only the digits 1 to6 on the tens counter 131.

The counter is driven by a gear 133 which itself is driven by one of thegears on the indexing Geneva peg wheel 100. In the preferred embodimentdescribed above, the indexing Geneva 100 turns through 120° for eachindexing operation and the gear on it has six teeth. The gear 133 hasfifteen teeth and engages with the twenty teeth 134 of the units counterillustrated in FIG. 19( a). Thus, the 120° rotation of the indexingGeneva 100 drives the units counter 130 through 36°. FIG. 19( a) showsthe units counter ring 130 viewed from behind the face on which thenumbers are formed.

A counter Geneva wheel 135 is shown located inside the units counterring 130 for mounting on a fixed post which is part of chassis 66.

An actuated peg 136 for the counter Geneva mechanism is located on theinner diameter of the units counter wheel 130. This peg 136 engages withone of the three indentations 137 in the Geneva wheel 135 causing theGeneva wheel 135 to rotate by 120° as the peg 136 passes by the wheel135 during its 36° rotation between displaying the digits 9 and 0.

It should be noted that in this Geneva mechanism, the peg 136 is on theouter larger diameter component 130 and this drives the slotted smallerwheel 135 whereas, for the indexing Geneva 100, the slots are on thelarger wheel and they drive the pegs on the smaller wheel. However, bothare examples of a Geneva type mechanism providing intermittent rotationwith accurate location between the rotations.

The Geneva wheel includes cant faces 138 which contact against the innerwall 139 of the units counter 130 preventing the Geneva 135 rotatingbetween indexing. To permit the Geneva 135 to rotate as it is pushed bythe peg 136, there is a gap 139 a in the inner wall 139 adjacent to thepeg 136.

The Geneva has a 3 tooth gear on its underside engaging with pegs on thetens counter ring to drive it.

FIG. 19( a) through to FIG. 19( e) show the positions of the Genevawheel 135, the drive gear 133 and the units counter 130 at four stagesduring the 36° rotation of the units counter.

FIG. 20( a) to FIG. 20( c) show the motion of the two counter wheels asthey index from 21 doses to 20 doses remaining, when only the outerunits counter 130 moves.

FIG. 20( c) to FIG. 20( e) show the corresponding situation from 20 to19 doses remaining where both counters index.

After the last dose has been used, the remaining doses display will read0 indicating that the device is empty to the user.

However, if the user does not look at the display, they may actuate thedevice again when desiring further doses.

It is preferable that the device provides some positive feedback to theuser, as it is being actuated, that it is empty.

This feedback can be in the form that the priming lever 8 cannot bemoved to its operating position with the level of force normally used.This tactile feedback provides a lockout feature.

A preferred method of achieving this with the two disc device is toarrange that after the last dose has been used, the second disc indexessuch that it has no pocket under the prodger. At this point, the twoprodger members 76 both face surfaces of the discs without pockets. Thusas the priming lever 8 is moved, neither prodger member 76 can move ontoa disc and the resulting force on the prodger members 76 is transmittedback through the drive mechanism to the priming lever 8 and hence to theuser.

Whilst the user may be able to apply sufficient force to move thepriming lever 8 through to its home position, this will only be possibleby forcing the discs to separate against the constraint of the casework.The force required to do this can be made sufficiently greater that thenormal actuation force as to be obvious to the user.

From the description, it can be seen that this mechanism provides aclear visual indication of the number of doses remaining with a minimalnumber of components.

The preferred embodiment described above is arranged consecutively todispense the powder from each pocket of one carrier and thensubsequently the powder from each pocket of the other carrier. However,it should be appreciated that it is also possible for a device todispense powder from pockets alternately from one carrier and then theother carrier. Alternatively, pockets of both disks may be dispensedsimultaneously.

By dispensing powder from both carriers, either one after the other orsimultaneously, it is possible for the user to inhale the powder fromboth carriers simultaneously. This arrangement is particularlyadvantageous when used with disks containing different medicament. Inparticular, it is preferred to provide disks containing a combination ofmedicaments that are more effective together than singularly. By way ofexample, a steroid compound could be dispensed from one disk and a longacting beta agonist (LABA) from the other disk for the treatment of, forexample, asthma or chronic obstructive pulmonary disease. Examples oflong acting beta agonists include formoterol and salmeterol and examplesof steroids include fluticasone propionate, budesonide and monetasonefuroate.

It is also possible to adapt the mechanism so to as to arrange forselective dispensing from one or both carriers. Where both disks areprovided with the same medicament, this may be used to vary thedispensed dosage.

Although a device has been described with reference to a particular typeof carrier, in particular having through holes and sealed with liddingsheets on either side, it is also possible to use other carriers, suchas more conventional blister packs. These could include inserts similarto those described above. However, alternatively, powder in the pocketsthemselves could outwardly burst the lidding sheet. Also certain aspectsof the device are applicable with other opening arrangements such aspeeling or cutting of the lidding sheet.

Finally, it should be appreciated that the device can be provided withcarriers pre-installed or, alternatively, ready for use with appropriatecarriers.

As illustrated in FIG. 13, the preferred arrangement described above canbe provided conveniently as three assemblies for use with carriers 12.In particular, a first cover sub-assembly A receives one carrier 12 anda second cover sub-assembly B receives another carrier 12. The two coversub-assemblies A and B are then secured to one another with a chassissub-assembly C therebetween.

The invention claimed is:
 1. A device for dispensing individual doses ofpowder from respective pockets of a carrier, the device including: firstand second supports rotatable about a central axis and for supportingrespective first and second carriers having cavities with respectivepockets formed therein and arranged in respective first and secondcircular arrays centred on the central axis; a changeover componentlocated between the first and second supports, the first support havinga first feature for engaging with the changeover component and thesecond support having a second feature for engaging with the changeovercomponent; an indexing mechanism arranged to rotate each of the firstand second supports; and a dispensing mechanism comprising anarrangement for axially moving, individually, each pocket from arespective storage position to a respective discharge position; whereinthe indexing mechanism is arranged to rotate the first support until thefirst feature engages the changeover component such that the firstsupport then moves the changeover component, the changeover componentbeing arranged to then engage the second feature so as to rotate thesecond support to a position from which the indexing mechanism isarranged to rotate the second support.
 2. A device according to claim 1wherein: the changeover component rotates the second support from aposition at which the indexing mechanism does not rotate the secondsupport and, when the first support moves the changeover component, thefirst support moves to a position in which the indexing mechanism doesnot rotate the first support.
 3. A device according to claim 2 wherein:when the second support is rotated back around to the position at whichthe indexing mechanism does not rotate the second support, consecutiveoperations of the indexing mechanism cause no rotation of eithercomponent.
 4. A device according to claim 1 wherein: the changeovercomponent is supported freely between and by the first and secondsupports.
 5. A device according to claim 1 wherein: each supportincludes a peripheral array of gear teeth; and the indexing mechanism isengageable with the gear teeth so as selectively to move the supportsand carriers.
 6. A device according to claim 5 wherein the indexingmechanism includes: priming member mounted for rotation about a centralaxis; and an intermittent-motion mechanism for interaction with thepriming member and gear teeth of the supports such that rotation of thepriming member from a first position to a second position causesrotation of at least one of the supports by a predetermined angle androtation of the priming member back from the second position causes norotation of the at least one of the supports.
 7. A device according toclaim 1 further including a dose counter having: a first counter ringhaving an indication of unit counts on a first display surface, thefirst counter ring being rotatable about a counter axis; a secondcounter ring having an indication of tens counts on a second displaysurface, the second counter ring being rotatable about the counter axis;and an intermittent-motion mechanism for driving the second counter ringfrom the first counter ring and rotating the second counter ring betweenconsecutive tens counts when the first counter ring rotates between twopredetermined consecutive unit counts.
 8. A device according to claim 7wherein the first counter ring is driven with rotation of the firstsupport.
 9. A device according to claim 7 wherein the counter axis iscoaxial with the first support.
 10. A device according to claim 7wherein: the first and second counter rings are positioned one withinthe other, with the first and second display surfaces adjacent eachother.